Power backhoe boom control



March 2, 1965 R. MOONEY, JR

POWER BACKHOE BOOM CONTROL Filed Dec. 8, 1961 7 m fi w fi 4? g 2 FIG. 2

FIG. I

INVENTOR RALPH MOONEY JR.

ATTORNEY United States Patent 3,171,553 PGWER BACKHOE 1560M CONTROL Ralph Mooney, In, Mahoning Ave, New Castle, Pa. Filed Dec, 8, 1961, Ser. No. 158,051 6 Claims. (Cl. 214-138) This invention relates to excavating apparatus, and more particularly to an improved arrangement for controlling the vertical swinging of the main boom of a poweroperated backhoe. In such apparatus where the main boom is pivoted on the forward end of a revolving power and control cab and the bucket-carrying arm is pivoted to the outer end of the boom it is often desired to either lock the boom in a predetermined vertical position or to controllably restrain the upward or downward move ment of the boom from such position. In heavy digging this action positively forces the teeth of the excavating bucket into the ground and in lighter or spot earth removal permits the path of movement of the bucket to be more precisely controlled. Heretofore hydraulic cylinders have been proposed for this general purpose of controlling the vertical swinging of the boom but these must be of large size to withstand the forces encountered, are difficult and awkward to install in the assembly, and are subject to considerable maintenance because of the exposure of their rods to the abrasive components of the excavated materials which are continuously drawn toward the location of the cylinders. Further, these cylinders must be of special construction and thus are very expensive, and have the further disadvantage of being unable to control the resistance to vertical movement of the boom. If the valve controlling the interchange of oil between opposite ends of a double-acting cylinder used for this purpose is fully closed, the boom is in effect locked to the power and control cab and acts as a lever to violently rock the same and the operator in it as the excavating bucket is drawn forwardly. Under such conditions the machine is difiicult to operate over long periods of time and is subject to excessive wear and tear as will be readily understood. Whether a double-acting cylinder as aforesaid or a single-acting cylinder to restrain only upward movement of the boom is used, partial opening of the control valve will result only in a control of the speed of movement of the boom without controlling the resistance to movement of the boom. As will appear hereinafter, the control of such resistance is a substantial improvement in the design and operation of conventional power-operated backhoes.

Accordingly, the primary object of the present invention is the provision of a practical and easily controlled mechanical arrangement for controlling the vertical pivotal movement of the main boom of a power-operated backhoe, which mechanical arrangement is operative to either lock the boom in any position of its possible path of travel with equal force or to adjustably control the resistance to movement of the boom in either direction from any position and with equal force. Ancillary objects of the invention is the provision of apparatus for the purposes indicated which is inexpensive, comprised of readily available components, easily installed, maintenance-free in operation, and capable of being very easily controlled by the operator of the equipment.

To accomplish the basic objects of the invention, I utilize one or a pair of heavy-duty truck-type wheel-brake assemblies parts of which are rigidly mounted on the main base frame of the power and control cab of the machine while cooperating parts are rigidly fixed to structural members of the swinging boom. This arrangement may be structurally arrived at in a number of different ways-either utilizing the conventional pivot lugs and pins used to mount the boom on the cab or by providing a more special construction such as herein illustrated and to be described below. It will be obvious to those skilled 3,171,553 Fatented Mar. 2, 1965 in the art that if the brake unit or units are to be applied to existing conventional boom mountings, it is only necessary that the hub and brake-drum section of a heavy-duty truck axle be adequately secured to the boom, for example, while the brake shoe section is adequately secured to the frame or base of the cab. Of course, the alignment must be such that the axis of the brake coincides with the pivotal axis of the boom.

A further and more specific object of the invention is the provision of an improved pivotal mounting for the main boom of a power-operated backhoe, which mounting incorporates the improved brake control for the vertical swinging movement of the boom.

The above and other objects and advantages of the invention will become apparent upon consideration of the following specification and the accompanying drawing wherein there is disclosed a representative embodiment of the invention.

In the drawing:

FIGURE 1 is a side elevation of a conventional poweroperated backhoe constructed in accordance with the principles of my invention; and

FIGURE 2 is a fragmentary section taken along the line IIII of FIGURE 1.

The apparatus illustrated comprises, in accordance with conventional design, a crawler-type of support ltl on which is swivably mounted a power and control cab 11 housing the power plant, winches, controls, etc. of the assembly. Normally, the cab 11 has a heavy base frame on which is mounted the various components aforesaid, and in the drawing this base frame is shown only schematically, being designated by the reference numeral 12. The vertically swingable boom of the apparatus is shown at 13, and various expedients of lugs, pins, etc. are commonly employed to pivotally connect the boom onto the forward edge of the base frame 12. Also in accordance with prior practice an arm 14 mounting an excavating bucket 15 is pivotally mounted at is on the outer end of the boom 13. As shown, the arm 14 is pivoted intermediate its ends and draw cables 17 and 18 connected to opposite ends of the arm 14 lead to suitably controlled power-operated winches, not shown, housed within the cab 11. By simultaneous control of the cables 17 and 18 the boom 13 may be raised and lowered and the arm 14 pivoted with respect to the boom to carry out the excavating sequences In the particular embodiment of the invention illustrated the two spaced side rails 20 of the boom 13 at the cab end of the boom are pivotally mounted on a heavy fixed axle 21 as shown in FIGURE 2 of the drawing. This axle 21 is rigidly mounted on the base frame 12. of the cab 11 by suitable means such as the spaced block 22 and the bolts 23.

The end portions of the axle 21 cantilever out over the block 22 and are provided at their extreme end portions with shoulders to receive the inner races of bearings 24. The outer races of these anti-friction bearings 24 are re ceived against shoulders formed in hubs 25. The ends of shaft 21 are threaded to receive the retaining nuts 26 whereby the hubs 25 are held against axial movement relative to the shaft 21. Suitable dust covers, not shown, may be provided to seal the bearings against the entrance of foreign matter.

As shown, the side rails 20 of the boom are apertured to allow passage of the axle 21 and lie flat against the innerfaces of the heavy flanges of the hubs 25. Overlying the innerfaces of the rails 29 are heavy integral flanges of brake drums 27. These drums as well as the rails 20 and the flanges of the hubs 25 are secured rigidly together by circles of heavy bolt 28 and, of course, the alignment of the parts as such that the brake drums 2-7 are concentric with the bearings 24.

Welded or otherwise rigidly secured to the axle 21 at the inner ends of the drums 27 are the disc-like brake shoe carriers 29 which, in accordance with conventional motor vehicle brake construction, carry brake bands 30 and hydraulic actuators or cylinders 31 for forcibly expanding the brake shoes into frictional engagement with the drums 27 whereby variable resistance to rotation of the drum with respect to the fixed axle 21 may be effected.

While the illustration in the drawing of the above outlined arrangement for pivoting and braking the excavator boom is more or less elementary and schematic, it should be understood that in actual practice the various parts comprised of the hubs 25, bearings 24, drums 27, discs 29, brake shoes 30 and cylinders 31 may all be conventional parts of heavy duty truck or trailer axles. Since such parts are made in large quantities for the trucking industry, they are remarkably inexpensive considering their size, strength and quality. Further, in such apparatus the diameter of the drums and the large brake surface area provides adequate torque resistance to lock the boom in any position even though only one braking unit is employed.

Hydraulic fluid under pressure is controllably supplied to the brake actuators 31 from any suitable source indicated schematically herein at 32. This source may comprise the lubricating oil pump on the main engine of the excavator or it may comprise a separate pump and reservoir with which such machines are often equipped to provide a source of hydraulic power for servo and control mechanisms. The flow of fluid pressure from the source to the brake unit or units is under the control of a pressure regulating valve 33 shown herein as having a hand-engageable operating lever 34, although it should be understood that the valve 33 may be foot controlled or automatically controlled in integration with other controls of the complete apparatus. Valve 33 is preferably of the kind which transmits variable pressure to the brake shoe actuators so that the amount of braking force or torque applied is controlled by the position of its actuator. Of course, it is also contemplated that a hand or foot operated master cylinder may be employed for this purpose whereby the braking effect is determined by the manual force exerted as in the case of an ordinary motor vehicle system. It should also be understood that, if desired, the hydraulic actuation of the brake or brake units employed may be replaced with air actuation, a transition which is well Within the skill of any truck servicemen.

It should now be apparent that I have provided an improved arrangement for controlling the movement of the main boom of the power-operated backhoe which accomplishes the objects initially set out. The ability to quickly lock the boom in any vertical position While yet enabling a variable resistance to movement in either direction to be applied enhances the usefulness and productivity of the excavating apparatus while keeping to a minimum the wear and tear on the operator and the machine. Thus, in excavating as in FIGURE 1, the initial downward position of the boom 13 may be maintained under predetermined torque at the brake which is insuflicient to rigidly lock the boom and to cause violent tilting of the cab 11 if a hard obstruction is encountered by the bucket 15. The movement control of my invention is further advantageous in that it may retain the boom in a desired upper position .and permits the boom to be closely controlled during its downward positioning independently of manipulation of the cables 17 and 18. Further, these improved results are obtained by the use of readily procurable and inexpensive components which are of such ruggedness as to require only very infrequent service and repair.

Since, as pointed out in various paragraphs above, many changes may be made in the adaptation of the principles of my invention without departing from the spirit or scope thereof, reference should be had to the appended claims in determining the scope of the invention.

I claim:

1. In a power-operated backhoe of the kind having a vertically swingable boom pivotally mounted at one end on a, power and control unit and pivotally mounting on its outer free end a bucket-carrying arm the improvement comprising (a) means to impart a variable resistance to swinging movement of said boom,

(b) said means to impart comprising a brake drum member and a brake shoe member and means to force said brake shoe member into frictional contact with said drum member,

(c) one of said members being mounted on said unit and the other of said members being mounted on said boom, and

(d) said drum member being concentric about the pivotal axis of said boom at said unit.

2. Apparatus according to claim 1 terized in that said means to force comprises an actuator operated by fluid pressure, and further including (2) means to supply fluid under variable pressure to said actuator.

3. In a power-operated backhoe of the kind having a vertically swingable boom pivotally mounted at one end on a power and control unit and pivotally mounting on its outer free end a bucket-carrying arm the improvement comprising (j) a shaft rigidly mounted on said unit,

(g) means journalling said boom on said shaft,

(a) means to impart a variable resistance to swinging movement of said boom,

(b) said means to impart comprising a brake drum member and a brake shoe member and means to force saidbrake shoe member into frictional contact with said drum member,

(11.) one of said members'being mounted on said boom and the other of said members being mounted on said shaft, and

p (i) said drum member being concentric about said shaft.

4. In a power-operated backhoe of the kind having a vertically swingable boom pivotally mounted at one end on a power and control unit and pivotally mounting on its outer free end a bucket-carrying arm the improvement comprising (j) A shaft rigidly secured intermediate its ends to said unit.

(k) hubs having inwardly facing flanges journalled on the cantilevered end portions of said shaft,

(I) said boom having transversely spaced rails over-. lying the inward faces of the flanges .on said hubs,

(m) inwardly open brake drums secured to the inner faces of said rails,

(It) said flanges, rails and drums being rigidly interconnected together at' either end of said shaft and said drum being concentric about said shaft,

(0) brake shoes mounted on said shafts, and

(p) means to force said shoes into pressure frictional contact with said drums.

5. In a power-operated backhoe of the kind having a vertically swingable boom pivotally mounted at one end on a power and control unit and pivotally mounting on its outer free end a bucket-carrying arm the improvement comprising (a) means to impart a variable resistance to upward swinging movement of said boom,

(b) said means to impart a variable resistance comprising a brake drum member and a brake shoe member and means to force said brake shoe memher into frictional contact with said drum member,

(0) one of said members being mounted on said unit.

and the other of said members having operative further charac- 5 connection with said boom to thereby resist the up- Ret'erences Cited in the file of this patent Ward swinging movement of said boom, and UNITED STATES PATENTS (d) said means to force said brake shoe member into frictional contact with said drum member including 2,873,871 Wane 17, 1959 means to vary said force to thus effect said variable 5 3,973,465 Stmad Jail 15, 1963 resistance to swinging movement of said boom. 3,117,586 BIOWII Jafl- 1964 6. Apparatus according to claim 5 further characterized in that said means to force said brake shoe member FOREIGN PATENTS into frictional contact with said drum member comprises 613,115 Germany M 17, 1935 fiuid-pressure-operated motive means, and means to vary 1() 1 130 7 2 France O 3 1956 the pressure of the activating fluid supplied to said motive means. 

1. IN A POWER-OPERATED BACKHOE OF THE KIND HAVING A VERTICALLY SWINGABLE BOOM PIVOTALLY MOUNTED AT ONE END ON A POWER AND CONTROL UNIT AND PIVOTALLY MOUNTING ON ITS OUTER FREE END A BUCKET-CARRYING ARM THE IMPROVEMENT COMPRISING (A) MEANS TO IMPART A VARIABLE RESISTANCE TO SWINGING MOVEMENT OF SAID BOOM, (B) SAID MEANS TO IMPART COMPRISING A BRAKE DRUM MEMBER AND A BRAKE SHOE MEMBER AND MEANS TO FORCE SAID BRAKE SHOE MEMBER AND MEANS INTO FRICTIONAL CONTACT WITH SAID DRUM MEMBER, (C) ONE OF SAID MEMBERS BEING MOUNTED ON SAID UNIT AND THE OTHER OF SAID MEMBERS BEING MOUNTED ON SAID BOOM, AND (D) SAID DRUM MEMBER BEING CONCENTRIC ABOUT THE PIVOTAL AXIS OF SAID BOOM AT SAID UNIT. 